The inherent drawbacks of reciprocating piston engines have long been known and hundreds if not thousands of efforts have been made to create rotary engines which deliver power from combustion or pressurized gas more directly in a rotary direction rather than into a reciprocating system which must then be converted into rotation by an eccentric.
The best known rotary engine is of course the Wankel machine, which utilizes a rotor which is pushed against a revolving eccentric which in turn through the utilization of the wedge principle, converts an angular force into a rotational force.
Other engines have been developed along the lines of the instant invention in which a central rotary cylinder moves either in a non-cylindrical casing, or in a cylindrical casing but as eccentric of the axis of the casing. Examples of this type of engine are shown in U.S. Pat. Nos. 3,437,079 and 3,955,540 both of which utilize a cylindrical rotor mounted eccentrically in a cylindrical cylinder, and U.S. Pat. No. 4,134,382 which utilizes a non-cylindrical rotor in an oblate casing.
This general type of rotary engine has the principal advantage that the force of expansion of the combustion gases is applied more directly in a rotary motion due to the generally radially extending blades which act as a pistons, than do most rotary engines, and certainly more than reciprocating engines. There is also an inherent simplicity in the valving function, which can generally be provided automatically as a function of the rotary cylinder or blades passing over open ducts so that the motion of the rotor or the blades themselves accomplish the valving function. One problem with this type of engine, however, is the wear of the bearing tips of the piston blades which wipe the interior of the casing surface, and which are difficult to lubricate in some manifestations of the blade piston concept. Due to the general flatness of the engine, however, they are relatively easy to stack so that even in the one cycle version, any number of units can be ganged out of phase to achieve a smooth rotary motion on a common shaft.